Thank you both Ella and Anna. Very good points about level. As you mention, elementary learners, both adults and children, may not have sufficient English to be able to communicate the range of language functions in a typical lesson in the target language. This means that either they can’t communicate as they want to (in English) or that they use L1. It’s important to have a clear policy about use of L1 in class: when learners can use it and how much we let them us.
Anna you also make a good point about when to use the L1 as a way of engaging learners, checking understanding of instructions or allowing learners to further evaluate their performance in the lesson.
Can you think of any other moments in which the use of L1 would be acceptable?
e.g. if a learner is upset for personal reasons and wants to talk to us.